Experimental Study Of The Effect Of Puerarin On Retinal Neovascularization

Objective To study the effect of puerarin on retinal neovascularization and investigate the mechanism. Method Fourty one-week-old kunming mice were randomly divided into normal group,75% oxygen treated group,puerarin injected group and 0.9%NaCI injected group.The normal group were fed in the normal environment.The other four groups were exposed to 75% oxygen to establish a model of retinal neovascularization. Mice in normal group received no treatment .The two puerarin treated groups were given puerarin by intraperitoneal injection at the dose of 0.5g.kg¹and 0.25g.kg^-1 respectively twice a day for five days while the 0.9% NaCI injected group was given steriled 0.9% NaCI .The mice were sacrificed on 17-dat-old,the eyes were enucleated and processed for histological examination and transmission electron microscopy .The effect of puerarin was assessed by counting the number of endothelial cells of new vessels extending from retina to vitreous of 4 μm sagittal retinal cross sections under the light microscope . Immunocytochemistry was performed on some of cross-sections of the retina by using an endothelial cell-specific antibody CD₃₁. Result The average number of endothelial cells of new vessels extending from retina to vitreous per eye of every group were 4 in the normal group ,270 in the 75% oxygen treated ,80 in the 0.5g.kg^-1 puerarin injected group ,139 in the 0.25g.kg^-1 puerarin injected group and 256 in the 0.9% NaCI injected group.The number of endothelial cells of new vessels in the puerarin treated group were much less than the 75%oxygen treated group(p<0.05).The number of endothelial cells of new vessels in the 0.9% NaCI injected group were as much as that in the normal group (p>0.05).By electronic microscopy examination the rod outer segment layer appeared thinner ,the rod outer segment was shorter ,the discs is partly unclear and vacuolar in the 75% oxygen treated group compared with the normal group. However in the puerarin treated groups the retinal ultrastructure was intact without over toxic reaction and the leision in the rod outer segment layer was unobvious. Immunocytochemistry staining showed CD31 positive cells localized in the vitreal side of the inner limiting membrane in the retinal sections of oxygen-treated eyes.Conclusion Intraperitoneal injection of puerarin had effective inhibition of the retinal neovascularization in the murine model of ischemia-induced retinopathy but little toxicity perhaps. Intraperitoneal injection of puerarin may protect the lesion of retinal ultrastructure caused by hypoxia.